Nanolasers from ZnO nanorods as natural resonance cavities

ZnO provides conditions for the formation of a variety of micro/nanostructures which act as laser resonators sustaining guided modes, whispering gallery modes, random lasing and a combination of them. The scanning cathodoluminescence spectra and images of a ZnO nanorod with two mirrors at the end faces are studied at 10 K. Emission peaks of bound excitons and edge luminescence are observed in the ultraviolet spectral region. The spatial distribution pattern of emission intensity corresponding to localized photon modes of the nanorod is recorded at different wavelengths. A new method of visualization of localized optical modes in micro- and nano-sized laser cavities is suggested. The lasing peaks display successive onset and saturation with increasing excitation power density, and fit well the expected resonance spectrum of guided modes in hexagonal ZnO nanorods (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)